Second derivative UV spectrophotometric determination of hydrochlorothiazide and hydrochlorothiazide-amiloride combination in tablets

Abstract

Assay procedures based on second-order derivative UV spectrometry (D₂) have been developed for the determination of hydrochlorothiazide and amiloride, alone or in combination, in tablets. Hydrochlorothiazide (2–12 μg/ml) and amiloride (2–7 μg/ml) can be determined separately by measuring the amplitudes of maximum-minimum D_2(278-264nm) and D_2(381-365nm), respectively. Combinations of amiloride (2–7 μg/ml) and hydrochlorothiazide (20–70 μg/ml) in ratios ranging from 0.08 to 0.3 can be determined using the simultaneous equations method with measurements of the amplitudes of maximum-minimum D_2(381-365nm), and D_2(334-312nm). The linearity of the calibration curves was excellent (r > 0.9993), the precision (RSD) better than 1.3% and relative error less than 1.5%. No spectral interferences from tablet excipients were found. Applications are given for the assay of commercial tablets and content uniformity test. The procedures proved to be suitable for a rapid and reliable quality control.